Hydrogen-induced reduction of axial stress in optical fiber cores

Radial distributions of axial stress across B/Ge- and Sn/Ge-codoped core fibers and a Corning standard single-mode fiber were measured before and after hydrogen loading under different conditions. A significant reduction of axial stress in the core of all investigated fibers is observed after hydrogen loading. The stress reduction in the core: of hydrogen-loaded fibers is irreversible and depends strongly on the core dopants and the fiber drawing tension. The hydrogen-induced core stress reduction is believed to be related to the reactions between hydrogen and drawing-induced defects in the fiber con. (C) 1999 American Institute of Physics. {[}S0003-6951(99)03104-6].